CHRYSLER 46RE DIAGNOSTIC TROUBLE CODE P1740

COMPLAINT: Some 2000-2001Ram Vans, Dakotas, Ram Trucks and Durangos, may exhibit a flashing Check Engine Light, caused by a DTC P1740, which is a Torque Converter Clutch or Overdrive Solenoid Performance fault.

CAUSE: The cause may be, a Reducing Pressure Exhaust orifice that is too small, which delays the pressure increase needed when the Torque Converter Clutch is applied. Find OBD2 Code Reader for help? Refer to Figures 2 and 3 for a partial hydraulic schematics explaining the Boost Valves function.

CORRECTION: Refer to Figure 1 to locate the Reducing Pressure Exhaust Orifice, which is in the Boost Valve Cover Plate. Remove the plate and enlarge the orifice shown to .069."Chrysler also provides a new Boost Valve Cover Plate which will already have the orifice enlarged.

Summary: The Boost Valve is stroked via Overdrive Clutch pressure or Lock-up Signal Pressure from the Lock-up Valve, while in 3rd or 4th gear. This drains the Reducing Pressure from the 3rd land of the Pressure Regulator Valve. This allows the Pressure Regulator Valve to move to the left, increasing Main Line Pressure.

Summary: The Boost Valve is stroked via Overdrive Clutch pressure or Lock-up Signal Pressure from the Lock-up Valve, while in 3rd or 4th gear. This drains the Reducing Pressure from the 3rd land of the Pressure Regulator Valve. This allows the Pressure Regulator Valve to move to the left, increasing Main Line Pressure.
NOTE: Increasing the diameter of the Reducing Pressure Exhaust orifice, will allow the Pressure Regulator Valve to stroke to the left at a faster rate which will allow Line Pressure to increase quicker for Torque Converter Clutch application and for the 4th clutch application.